CMakeLists: Don't explicitly cherry-pick warnings as errors.

We the WARNINGS_AS_ERRORS CMake flag to treat all warnings as errors.

This change demotes the cherry-picked warnings-as-errors to just regular warnings, which can be optionally treated as errors like every other warning (WARNINGS_AS_ERRORS defaults to enabled).

Based on the discussions:
https://swiftshader-review.googlesource.com/c/SwiftShader/+/29810/6#message-de0432365b25c83372bac2f6528c79174aef0f6b
and
https://swiftshader-review.googlesource.com/c/SwiftShader/+/30191/2/CMakeLists.txt#248

Bug: b/135472272
Change-Id: I8aa37d79b9263560f9ff55ad4817f66ded6960ee
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/32953
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 86fc3fa..ad6b2cb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -333,17 +333,17 @@
 
     list(APPEND SWIFTSHADER_COMPILE_OPTIONS
         "-Wall"
-        "-Werror=reorder"
-        "-Werror=sign-compare"
-        "-Werror=missing-braces"
+        "-Wreorder"
+        "-Wsign-compare"
+        "-Wmissing-braces"
     )
 
     if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
         list(APPEND SWIFTSHADER_COMPILE_OPTIONS
-            "-Werror=unused-lambda-capture"
-            "-Werror=string-conversion"
-            "-Werror=extra-semi"
-            "-Werror=ignored-qualifiers"
+            "-Wunused-lambda-capture"
+            "-Wstring-conversion"
+            "-Wextra-semi"
+            "-Wignored-qualifiers"
             # Silence errors caused by unknown warnings when building with older
             # versions of Clang. This demands checking that warnings added above
             # are spelled correctly and work as intended!